Method of and multiplex selective system for transmitting radiant energy



June 12, 1928. 1,673,562

H. HAMMOND. JR

J. METHOD OF AND MULTIPLEX SELECTIVE SYSTEM FOR TRANSMIT'IJING RADIANT ENERGY Original Flled March 22, 1917 5 s t -s 1 5? .Ja. lllli m 56 12 35 MIN j WITNESS INVENTOR I r! I fl/l I I 6 a;

HIS ATTORNEY June 12, 1928. 1,673,562

J. H. HAMMOND. JR METHOD OF AND MULTIPLEX SELECTIVE SYSTEM FOR TRANSMITTING RADIANT ENERGY Original Fi e March 1917 s Sheets-Sheet 2 will a l N l l l INVENTOR WITNESS 7' I l,, I V I y h I I I H/s ATTORNEY June 12, 1928. 1,673,562

J. H. HAMMOND. JR METHOD OF AND MULTIPLEX SELECTIVE SYSTEM FOR TRANSMITTING RADIANT ENERGY Original Filed March 191,7 3 Sheets-Sheet 5 WITNESS INVENTOR an, 7 1 I V n l I i W HITS ATTORNEY.

Patented June 12 1 PATENT OFFICE.)

JOHN HAYS HAMMOND, an, or eroucnsrnn, MAssacHosnrrsQ METHOD OF AND MULTIPLEX SELECTIVE SYSTEM ENERGY.

non TRANSMITTING RADIANT Application filed March 22, 1917, Seria1 N0.156,700. Renewed. June 15, 1926.

Some of the objects of this invention are to provide a'multiplex selectlve transm ssion system which may be controlled from a pin rality of distant points'or stations; to provide a multiplexselective transmission system which may be controlled by a plurality of operators acting either separately or simultaneously; to provide a method and multiplex selective transmission system whereby a pluralityof operators may transmit either separately 1 or simultaneously a plurality of different series of electroradiant oscillations; .to provide an improved multiplex system for radio telephony; and to provide other improvements as will appear hereinafter. i I i a In the accon'ipanying drawings, Fig. 1 is a diagrammatic view of a multiplex selective transm1ssion system for radiantenergy constructed in accordance with this invention; Figs. 2 and 3 are side elevations of de tails of the same;

Fig. 4 is a diagrammatic view, of parts which may be substituted for certain of the parts shown in. Fig, 1;

Fig". 5 is a diagrammatic view of a further,

modified multiplex selective system 1 constructed in accordance with this invention; and

Figs. 6 and";- are diagrammatic views respectively of a multiplex transmission system for radio telephony and a. multiplex receiving system for use withthe transmission system. 1

Referring to the drawings and particularly to Fig. 1, one embodiment of this invention I comprises a multiplex selective transmission system including an antenna 10 or open aerial circuit, which has in series therewith a coil 11 and which is grounded at 12. The coil 11 forms the secondary of a t 'ansformer 15, the primary coil 16 of which is connected at one end through a conductor 17 to one side of the variable condenser 18. Connected to the other side of the condenser 18 is a conductor 19 which in turn is slidahly connected to a rotary member 20 of a spark gap device 21. The spark gap device 21 includes a casing 22 surrounding the rotary member 20 and a stationary conducting terminal 23 which is connected by a conductor therotary member 20, which is made of copper or any other suitable conducting material, is in the form of a disk which is rigidly secured to a shaft 25 coaxial therewith and designed to be rotated about its longitudinal axis at a predetermined rate. The disk 20 and shaft 25 areinsulated from the casing 22. :The" disk 20 is provided upon one side with a plurality of radial projections 26 integral therewith and the outer surfaces of which arearranged in a plane perpendlcular to the shaft 25 and spaced slight.

ly away fronrthe stationary terminal 23. The stationary terminal 23 is oifthe same form and CllHlGHSlODS indront elevation as any one or several of the projections 26, and is arranged so that as the disk 20 is rotated. the projections 26 are'brought successively into position opposite the projections of the stationary terminal 23. The stationary ter-; minal 23is made of copper or any other suitable conducting material; and is insulated from the casing A container 30 secured to the lowerside of the casing 22 is filled with alcohol, or any other substance which gives off a vapor rich in hydrogen, and is providedwith a wick 31, whereby the alcohol is fed into the interior of the casing in the form of a vapor to keep the interior of the casing filled with an atmosphere rich in hydrogen to assist in the quenching action of the spark gap device. 4 e

For energizing the oscillatory circuit including the primary coil 16, the condenser 18 and the spark gap device 21, an alternating current generator 35 is arranged to sup ply alternating current to a circuit which. has in series therewith a coil 36 forming the primary of atransformer 37, the secondary 38 of which'is connectedat one end by a conductor 39'to the conductor 17 leadmg to one side of the. condenser 18, and is connected at its other end by a conductor 4-0 to the conductor 19 on the other side of the condenser 18. Connecting the conductors 39 and 10 are two'tone circuits; One

of these tone circuits includes an inductance 15, a variable condenser 46 and a pivoted switch 47 which is normally held open by a spiral spring 48. The other of these tone circuits includes an inductance 5 0,a variable condenser 51and a. pivoted'switch 52, which is normallyheld open by aspiral spring 53. The switch 17 of the firstinen tinned tone ircuit isarranged to beacon;-

trolled by an electromagnet 55, which is in a circuit including a battery'56 or other source iii 1 in operation.

of electric energy and a switch or key 57 whereby the circuit is controlled. The switch 52 of the other tone circuit is arranged tov be controlled by aneleetromagnet 60, which is in a circuit including a battery 61 or other source of electric energy and a switch or key 62 whereby the circuit is controlled. The switches or keys 57 and (32 may bearranged at any desired distant concontrol points. Other tone circuits might be added between the conductors 39'and 40, so as to permit any one of a number of opcraters to control' the system separately. The tone circuits are tuned to different frequencies respectively, forinstanee', to twenty thousand per second and ten thousand-per second.

In the operation ofthe system shown in Fig. 1, when either of the switches or keys ,57 and '62 is closed, the corresponding tone circuit 4-5, 46 or-50,,51 is thrown into action, and corresponding groups of oscillations at a predetermined group frequency and oscillationyfrequency are produced in the circuit including the primary coil 16, the condenser 18 and the spark gap device 21. The spark gap device 21. acts to divide these groups of-oscillations into sets of groups having a predetermined setfrequency depending upon the number of radial projections 26 upon the rotary member 20 of the spark gap device, and the rate. of rotation of the rotary member 20. This set frequency might be, for instance, five hundred per second. These sets of groups of oscillationsenergize the antenna 10 through .the action of the secondary coil; 11 and cause the antenna 10 to emit sets of groups of electroradiant oscil-v lations having a predetermined wave frequency which is the natural frequency of oscillation of the antenna and which would ordinarily be about one million per second.

i a set frequency controlled by and thesame as the frequency of the spark gap device 21, and a group frequency controlled by and the same as the group frequency of the par ticular tone circuit 45, 4G, or 50, 51 which is It is-to1 be understood that a suitable selcctii e receivingi'systcm is provided for selectively receiving the two different series of sets of groups of electroradiant oscillations.

The system: shown in Fig. 1 may be modified by substituting for the transformer 37 y and alternator 35, a direct current generator 65, or other suitable source of direct current, as shown in Fig. 4, without otherwise changing the system.

The form of this invention shown in Fig; 5 comprises an-antenna 200grounded at 201, and having in series therewith a coil 202 which forms the secondary of a transformer 203; The primary coil 204s of the transformer 203 is in a closed oscillatory circuit including. a. condenser 205 and is supplied with electric energy by a high frequency alternator 206 or other source of alternating current/ F or controlling the operation of the antenna 200, a point of high potential of the antenna is connected by a conductor 210 with a plate 211 of a pliotron or highly vacuized audion form of electronic relay 212. This pliotron includes a highly vacuized glass bulb or container 214. in which the plate 211 is located and in which are also located a grid 215 and a filament 216. The filament'216 is connected in series'with a battery 217 whereby the filament is heated. The grid 215 is connected to one end ofa conductor 218-the other end of which is connected to two conductors 219 and 220 one of which leads to the circuit of the battery 217 and the other of which leads to a suitable ground 221. The conductor 218 contains twocoils 225 and 226 which form the secondary coils of two transformers 227 and 228, the primary coils 229 and 230 of which are connected intwo normally open circuits 235 and 236 controlled by normally open switches 237 and 238, and arranged to be energized respectively by two high frequency alternators 239 and 240 which are operated: so as to produce in the coils 229an'd 230 respectively two series of electrical oscillations of different predetermined frequencies respectively. The two switches 237 and 238 are arranged to be controlled by two electromagnets'245 and 246 which are contained in two: circuits 247 and 24:8 provided respectively with two switches or keys 249 and 250 and arranged to be energized respectively by two batteries 251 and or other sources of electric energy. The two switches or keys 249 and 250 may be located at any desired distant control points.

In the operation of the system shown in Fig. 5, the antenna 200 is energized at; a result of the operationof the high frequency alternator 206. and is caused to emit electroradiant oscillations having a wave. tlrcquency determined by-tlie naturalfrequency of oscillation' of the antenna 200. The circuits of thepliot'ron 212 RIOS-J0 adjusted that normally no current flows from. the antenna 200 tothe platc2'll. but when either of the switches 249 or 250is closed; the corresponding magnet 245 or 246 will he energized. thus closing the corresponding circuit: 235 or 236 and causing electrical oscillations to he set up' in the correspondingprimary coil 229 or: 230. These oscillations in the primary coil229 or 230 produce electrical oscillations of a corresponding frequency in the C()t'!(3- sponding secondary coil 225 or 226. and the. oscillations in the secondary coil 225 or 226 not upon the grid 215 to vary the potential of the grid periodically with a frequency notation corresponding to the frequeney'ol the oscillations thus produced in the secondary coil or 226. The variations in the potential oi the grid 215 causes electric energy to flow periodically from the antenna 200 through the conductor 210, pliotron 212, conductor- 219 and conductor 220 to the ground 221. lVhenever a flow of energy thus occurs from the antenna 200 through the pliotron 212, a damping effect will be produced in the emission oi?- the high frequency waves from the antenna. and periodic variations in the amplitude of the elcctroradiant oscillations emitted by the antenna will thus be produced, the frequency of these variations being the sameas the frequency of the alternator 239 or 240 the circuit of which happens to be closed. Whenboth switches or keys 249 or are closed, two series of periodic variations in the amplitude of the electroradiant oscillations emitted by the antenna 200 will be produced, the frequencics of these two series corresponding; to the frequencies of the two alternators 239 and 240. It isto be understood that any well known or suitable receiving system or systems may be provided for receiving the electroradiant oscillations thus emitted by the antenna 200, such receiving system or systems being provided with receiving circuits or devices tuned respectively to the several frequencies of the transmission system.

In Figs. 6 and 7 of the drawings, this invention is shown applied in a multiplex radio telephone system, including a transmission system shown in Fig. 6, and a re. cciving system shown in F 7. The trans mission system shown in Fig. 6 includes an antenna 300 grounded at 301, and having in series therewith a coil 302 which forms the secondary of a transformer 30 3 which includes a nimary coil 30% one end of which is connected by a conductor 305 leading through a choke coil 306 to one brush 307 of a direct current generator 308, the other brush 309 of the generator being connected through a choke coil 310, conductor 311 and spark gap device 320 to the other end of the primary coil 304. A condenser 321 is con n-ectcd between the conductors 305 and 311;

instance, at 30,000 interruptions per second,

Instead of exciting the antenna 300 by the system just described and including the direct current generator 308 and spark gap device 320, the antenna 300 might be excited by the system shown in Fig. 5, and hereinbeforc described, and including the alternator 206, or the antenna300 might be ex cited in any other suitable manner.'

For controlling the operation of the an tenna 300, a point of high potential of the antenna is connected by a conductor 330 with the plate 331 of a pliotron or highly vacuized audion form of electronic relay This pliotroir includes a highly vacuized glass bulb or container 333 in secondaries otthre'e transformers 355, 356,

and357, the primary coils 3 60, 361 and 362 of whlch are contained 111 three separate circults 36land 365 which are arranged to be energized respectively'by three high frequency electrical alternators 370, 371 and i 372 and to beqcontrolled in a wellknow'n manner by three telephone transmitters 373, 374 and 375, and by three normally open switches 37 6, 377 and 378. The three alternators 370, 371 and are arranged to be operatedin such a manner as to producerespectively three-series of electrical oscillations having three different predetermined Jun fre uencies res )ectivel for instance 'li're quencies of 10,000, 15,000 and 20,000 oscillations per second. I

In the operation of the transmitting systern shown in Fig; 6, the antenna 300 is energized as a result of the operation of the direct current generator 308 acting through the spark gap device 320 and the primary coil 30 i, and is thus caused to emit clectroradiant oscillations having'a. wave frequency equal to the natural oscillation frequency of the antenna.

The circuits of the pliotron 332 are so adjustedthat normally no current flows from the antenna through the conductor 330 and'pliotron when any one/o1 the switches 376, 377 or is closed; oscillations will be produced in the corresponding primary coil 360, 361 or 362 by the corresponding alternator 370, 371 or 372. H l

It now the corresponding telephone transmitter 373, 37a or 37 5 be operated inresponse to sound waves, electrical oscillations corresponding to the sound waves rew ceived will be impressed upon the electrical oscillationsproduced'in the coil360. 361 or 362 by the corresponding alternator 370, 371 or 3 2. These combined oscillations will act inductively uponthe corresponding seeondary coil 350, 351 or 352, and will produce corresponding combined oscillations in the conductor 340, which will act upon the grid 334 of the pliotron 332 and will cause corresponding variations in :the potential of the grid. Variations in the potentiallof the grid 334 cause a correspondingly varied flow of electrical energy from the antenna 300 through the conductor 330 and pliotron 332, thus producing corresponding variations in the amplitude of the clectroradiant oscillations emitted by the antenna 391-). When two or more of the switches 376, 377 and 378 are closed at the same time and when the corresponding telephone transmitters 373, 374 or 375 are operated, a correspond ing plurality of series of electrical oscillationswill be simultaneously set up in he conductor 340, each series of oscillations having impressed thereon undulations or oscillations corresponding to sound waves received by the corresponding. telephone transmitter 373, 374 or 375. and these variationswill cause corresponding variations in the potential of the grid 334 and thereby produce corresponding variations in the waves of radiant energy transmitted by the antenna300. In this manner, the antenna 300 may be caused to emit waves having im pressed thereon any one or more of a plurality of series of periodic variations having dili erent frequencies respectively corresponding to the different frequencies of the alternators 370, 371 and 372, and each series having impressed thereon amplitude variations corresponding to sound waves received by the transmitter 373, 374 or 375.

The multiplex radio receiving system shown in Fig. 7, includes an antenna 400 grounded at 401, and having in series therewith a coil 402 which forms the primary of a transformer 403 having a secondary coil 404 which is arranged in a closed oscillatory circuit including a variable condenser 405. This closed circuit 404, 405 is tuned to the wave frequency of the antenna 300 of the transmission system shown in Fig. 6, and is arranged to control a detector 4 10 constructed as hereinbe'fore described. The detector 41 0 is arranged to control a circuit 411 having in series therewith th'ree coils 41-2, 413 and 414, and a battery or other source of energy 415. These three coils 412, 413 and 414 form the primaries of three transformers 420. 421 and 422, which include respectively three secondary coils 425, 426 and 427. connected respectively in three closed oscillatory circuits including variable condensers 430, 431 and 432, the closed circuits being arranged to control re spectively three detectors 435, 436 and 437. These detectors control respectively three circuits 438.439 and 440, which include respectively three telephone receivers 441,442 and 443 and three batteries 444, 445 and 446.

revasee The three closed circuits which include respectively the three coils 42%, 426 and 427 are tuned to respond respectively to the three frequencies of the alternators 370, 371 and 372 of the transmission system shown in Fig. 6. When any one of the switches or keys 37(3, 377 and 378 of the transmission system shown in Fig. 6 is closed, and the corresponding telephone transmitter 373, 37 4 or 375 is operated. corresponding variations will be produced in the waves transmitted by the antenna 300. and these variations will cause corresponding variations in the circuit 411 controlled by the receiving detector 410, and the electrical oscillations produced by the sound waves impressed on the telephonic transmitters 373, 374 and 375 will be selectively received by the three telephone receivers 441, 442 and 443. Several telephonic messages may thus be simultaneously transmitted and simultaneously received by a corresponding number of operators.

It is to be understood that any of the hercinbefore described transmission systems may be used to operate either a single receiving system having a plurality of cooperating circuits or devices tuned to respond selectively to the different frequencies of the transmission system, or to operate a plurality of separate receiving systems having circuits or devices which are tuned to respond respectively to different frequencies of the transmission system. Any one of the transmission systems hereinbefore described mightbe used to control a plurality of recciving, systems located on a plurality of torpedo boats or other movable bodies, and arranged in a well known manner to control the direction of movement in each case, and to perform other functions in each case at the will of an operator. It is therefore evident that this invention provides a system whereby several operators located at (lib ferent control points may control a plurality of torpedo boats or other movable bodies respectively, through the operation of a single transmission station, the arrangement being such that each operator controls only a corresponding one of the boats or movable bodies. and that the operators may not either separately or simultaneously through the same transmission station.

Although only a few of the various tems in which this invention may be cmbodied have been shown herein, it is to be understood that the invention is not limited to any particular system but might be cmbodied in various systems without departing from the spirit of the invent ion or the scope of the appended claim.

Having thus fully described this invention, I claim, and desire to protect by Letters Patent of the United States:

A multiplex transmission system for HID radiant energy comprising, an antenna circuit including an inductance, a high frequency oscillation generator, the output of which is inductively coupled to said inductance, an amplifier, having an output circuit and an input circuit, the output circuit of Which is shunted around said inductance, a plurality of iiiduetances included 111 the 111- put circuit of said amplifier, and a circuit associated with each of said inductances each of said circuits comprising a source of different lower frequency oscillations and a microphone for voice modulating the amplitude of the last mentioned oscillations and said circuits being adapted to modulate, through said ainpliiying means, the high frequency oscillations radiated by said antenna in ZLCCOl'ClZLIlCfiXS llill said plurality of oice modulated lower frequency oscillations.

Signed at Gloucester in the county of 

